Tag: chemical reactions

Quizzes (8) Questions (144)

Questions Related to chemical reactions

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

An acidic solution of Cu+ salt containing 0.4 g of Cu+ is electrolysed until all the Cu is deposited. The electrolysis is continued for 7 more minutes with volume of the solution kept at 100 ml and the current at 1.2 amp. Calculate volume of the gases evolved at NTP during entire electrolysis( atomic weight of Cu= 63.6)

  1. H2 = 68.32 ; O2 = 85.23 ml

  2. H2 = 40.34 ; O2 =70.12 ml

  3. H2= 51.46 ; O2 = 90.12 ml

  4. H2=58.46 ; O2 = 99.68 ml
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This is a complex stoichiometry and electrolysis problem. After Cu+ is deposited, the electrolysis of water occurs (2H2O -> 2H2 + O2). Calculating moles of electrons from current and time, then applying Faraday's laws, leads to the volumes of H2 and O2 evolved.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

An electrolytic cell was set up. Distilled water is placed in the cell and battery is switched on. The bulb is also connected through a battery. The bulb will:

  1. glow

  2. not glow

  3. partially glow

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Distilled water is a bad conductor of electricity. It do not contains any impurities to carry the current. So the circuit will not be completed for the bulb to glow.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

Given below are the half cell reactions

${ Mn }^{ 2+ }+{ 2e }^{ - }\longrightarrow { Mn }  E=-1.81V$

$2\left( { Mn }^{ 3+ }+{ e }^{ - }\longrightarrow { Mn }^{ 2+ } \right) E=+1.51V$ will be

        




  1. 0.33V ; the reaction will not occur .

  2. 0.33V ; the reaction will occur.

  3. 2.69V ; the reaction will not occur.

  4. 2.69V ; the reaction will occur
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

To find the cell potential, we combine the half-reactions. The overall reaction is 3Mn^2+ -> Mn + 2Mn^3+. The E_cell = E_cathode - E_anode. Using the given values, E_cell = 1.51 - 1.81 = -0.30V. Since E is negative, the reaction is non-spontaneous.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

The first step in the extraction of Cu from copper pyrites is?

  1. Reduction by carbon

  2. Electrolysis of ore
  3. A Roasting of ore in $O _2$

  4. Magnetic separation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Copper pyrites (CuFeS2) contain iron and copper sulfides. The initial step in extracting copper from copper pyrites is roasting the ore in the presence of oxygen to remove excess sulfur as sulfur dioxide and convert iron sulfide into iron oxide.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

Conductivity ($\kappa $) of $0.01M$ $NaCl$ solution is $0.000145S$ ${cm}^{-1}$. What happens to the conductivity if extra $100mL$ of ${H} _{2}O$ be added to the above solution?

  1. Decreases

  2. Increases

  3. Remains unchanged

  4. First increase and then decrease
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Conductivity (kappa) is defined as the conductance of a solution contained between two electrodes of unit area and unit distance apart. Adding water (dilution) decreases the number of ions per unit volume, thus decreasing the conductivity.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

Which of the following is/are always true electroplating ?

  1. Copper is used as cathode

  2. Cathode always gins weight while anode always loses weight

  3. Iron is coated with nickel or chromium to prevent from rusting.

  4. Ammeter reading during. electroplating steadily decreases.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In electroplating, the object to be plated is the cathode. While the cathode gains weight, the anode only loses weight if it is made of the metal being plated (sacrificial anode). Option A is the most general correct statement regarding the setup.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry
Assertion: The conductance of electrolyte solution increases with temperature.
Reason: With increase of temperature the ionic mobility increases.

  1. Both Assertion and Reason are true and Reason is the correct explanation of Assertion

  2. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion

  3. Assertion is true but Reason is false

  4. Assertion is false but Reason is true

  5. Both Assertion and Reason are false
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

With increase of temperature the ionic mobility increases.